PRAS40 Connects Microenvironmental Stress Signaling to Exosome-Mediated Secretion

Extracellular domain mutations of the EGF receptor differentially modulate high-affinity and low-affinity responses to EGF receptor ligands

The EGF receptor is mutated in a number of cancers. In most cases, the mutations occur in the intracellular tyrosine kinase domain. However, in glioblastomas, many of the mutations are in the extracellular ligand binding domain. To determine what changes in receptor function are induced by such extracellular domain mutations, we analyzed the binding and biological response to the seven different EGF receptor ligands in three common glioblastoma mutants-R84K, A265V, and G574V. Our data indicate that all three mutations significantly increase the binding affinity of all seven ligands. In addition, the mutations increase the potency of all ligands for stimulating receptor autophosphorylation, phospholipase Cγ, Akt, and MAP kinase activity. In all mutants, the rank order of ligand potency seen at the wild-type receptor was retained, suggesting that the receptors still discriminate among the different ligands. However, the low-affinity ligands, EPR and EPG, did show larger than average enhancements of potency for stimulating Akt and MAPK but not receptor autophosphorylation and phospholipase Cγ activation. Relative to the wild-type receptor, these changes lead to an increase in the responsiveness of these mutants to physiological concentrations of ligands and an alteration in the ratio of activation of the different pathways. This may contribute to their oncogenic potential. In the context of recent findings, our data also suggest that so-called "high"-affinity biological responses arise from activation by isolated receptor dimers, whereas "low"-affinity biological responses require clustering of receptors which occurs at higher concentrations of ligand.

The Regulation of Exosome Generation and Function in Physiological and Pathological Processes

Exosomes, a type of extracellular vesicle with a diameter of approximately 100 nm that is secreted by all cells, regulate the phenotype and function of recipient cells by carrying molecules such as proteins, nucleic acids, and lipids and are important mediators of intercellular communication. Exosomes are involved in various physiological and pathological processes such as immunomodulation, angiogenesis, tumorigenesis, metastasis, and chemoresistance. Due to their excellent properties, exosomes have shown their potential application in the clinical diagnosis and treatment of disease. The functions of exosomes depend on their biogenesis, uptake, and composition. Thus, a deeper understanding of these processes and regulatory mechanisms can help to find new targets for disease diagnosis and therapy. Therefore, this review summarizes and integrates the recent advances in the regulatory mechanisms of the entire biological process of exosomes, starting from the formation of early-sorting endosomes (ESCs) by plasma membrane invagination to the release of exosomes by fusion of multivesicular bodies (MVBs) with the plasma membrane, as well as the regulatory process of the interactions between exosomes and recipient cells. We also describe and discuss the regulatory mechanisms of exosome production in tumor cells and the potential of exosomes used in cancer diagnosis and therapy.

Hypoxic regulation of extracellular vesicles: Implications for cancer therapy

Extracellular vesicles (EVs) play a pivotal role in intercellular communication and have been implicated in cancer progression. Hypoxia, a pervasive hallmark of cancer, is known to regulate EV biogenesis and function. Hypoxic EVs contain a specific set of proteins, nucleic acids, lipids, and metabolites, capable of reprogramming the biology and fate of recipient cells. Enhancing the intrinsic therapeutic efficacy of EVs can be achieved by strategically modifying their structure and contents. Moreover, the use of EVs as drug delivery vehicles holds great promise for cancer treatment. However, various hurdles must be overcome to enable their clinical application as cancer therapeutics. In this review, we aim to discuss the current knowledge on the hypoxic regulation of EVs. Additionally, we will describe the underlying mechanisms by which EVs contribute to cancer progression in hypoxia and outline the progress and limitations of hypoxia-related EV therapeutics for cancer.

Exosomes in the Diagnosis and Treatment of Renal Cell Cancer

Renal cell carcinoma (RCC) is the most prevalent type of kidney cancer originating from renal tubular epithelial cells, with clear cell RCC comprising approximately 80% of cases. The primary treatment modalities for RCC are surgery and targeted therapy, albeit with suboptimal efficacies. Despite progress in RCC research, significant challenges persist, including advanced distant metastasis, delayed diagnosis, and drug resistance. Growing evidence suggests that extracellular vesicles (EVs) play a pivotal role in multiple aspects of RCC, including tumorigenesis, metastasis, immune evasion, and drug response. These membrane-bound vesicles are released into the extracellular environment by nearly all cell types and are capable of transferring various bioactive molecules, including RNA, DNA, proteins, and lipids, aiding intercellular communication. The molecular cargo carried by EVs renders them an attractive resource for biomarker identification, while their multifarious role in the RCC offers opportunities for diagnosis and targeted interventions, including EV-based therapies. As the most versatile type of EVs, exosomes have attracted much attention as nanocarriers of biologicals, with multi-range signaling effects. Despite the growing interest in exosomes, there is currently no widely accepted consensus on their subtypes and properties. The emerging heterogeneity of exosomes presents both methodological challenges and exciting opportunities for diagnostic and clinical interventions. This article reviews the characteristics and functions of exosomes, with a particular reference to the recent advances in their application to the diagnosis and treatment of RCC.

Hypoxia derived exosomes promote the proliferation and metastasis of colorectal cancer through the regulation of HIF-1α/miR-4299/ZBTB4

AIMS

The biological functions of colorectal cancer (CRC) cell derived exosomes responding to hypoxic microenvironment and its underlying mechanisms remain unclear.

MAIN METHODS

Extracted exosomes were confirmed. CRC cells were incubated with hypoxic and normoxic exosomes and its biological behavior were analyzed. miRNA microarray were conducted. Cells were incubated with miRNAs mimics, inhibitors, or small interfering RNAs; expression of reporter constructs was measured in luciferase assays. Cells were transfected with Lentivirus vectors containing eGFP-miR-4299 overexpression (or ZBTB4 siRNA expression plasmid) and they were injected into BALB/C nude mice subcutaneously or by tail vein and the growth of xenograft tumors or lung metastasis were measured. The clinical significance of ZBTB4 was measured in tumor tissues and adjacent non-tumor tissues.

KEY FINDINGS

Hypoxic exosomes could tranfer to the recipient normoxic cells and promote the cell proliferation and migration. We found several miRNAs were significantly up-regulated in hypoxic exosomes and the expression levels of miR-4299 increased in both hypoxic cells and hypoxic exosomes. We observed that miR-4299 was upregulated in a HIF-1α dependent way. In addition, ectopic expression of miR-4299 promoted the tumor growth and metastasis in vitro and in vivo. ZBTB4, an identified direct target of miR-4299, could abrogate the effect on tumor growth and distant metastasis. The expression of ZBTB4 were decreased in tumor tissues compared with non-tumor colon tissues from patients.

SIGNIFICANCE

We demonstrated that in response to hypoxia, CRC cells had an increased production of exosomes. The hypoxia derived exosomes promote the proliferation and metastasis of colorectal cancer by exporting miR-4299 and modulating its target gene ZBTB4.

Fibronectin and JMJD6 Signature in Circulating Placental Extracellular Vesicles for the Detection of Preeclampsia

Preeclampsia (PE) is a major obstetric complication that is challenging to predict. Currently, there are limited tools to assess placental health/function in crucial gestational periods for diagnosis and early prediction. The glycoprotein fibronectin (FN) is augmented in PE placentae, and associated with reduced activity of JMJD6, an oxygen sensor that regulates placental FN processing. Evidence implicates placenta-derived small extracellular vesicles (sEVs) in the pathogenesis of pregnancy-associated disorders. Here, we examined the utility of FN and JMJD6 in placental sEVs as putative markers for early- and late-onset PE (E-PE and L-PE). Maternal plasma was obtained from venous blood collected longitudinally during pregnancy (10-14, 16-22, and 26-32 weeks of gestation and at delivery) in normotensive term control, preterm control, L-PE, E-PE, and gestational hypertensive individuals. Placenta-derived sEVs were isolated and their FN and JMJD6 content and JMJD6 activity were measured. In women that went on to develop preeclampsia, FN content of circulating placental sEVs was significantly elevated as early as 10 to 14 weeks of gestation and remained augmented until the time of delivery. This was accompanied by a depletion in JMJD6 content. Multivariate receiver operating characteristic analysis revealed high predictive power for FN and JMJD6 as early markers of E-PE and L-PE. In vitro, hypoxia or JMJD6 loss promoted FN accumulation in sEVs that was reverted on restoring cellular iron balance with the natural compound, Hinokitiol. Elevated FN, along with diminished JMJD6 in circulating placental sEVs, serves as an early molecular signature for the detection of different hypertensive disorders of pregnancy and their severity.

Extracellular Heat Shock Protein-90 (eHsp90): Everything You Need to Know

“Extracellular” Heat Shock Protein-90 (Hsp90) was initially reported in the 1970s but was not formally recognized until 2008 at the 4th International Conference on The Hsp90 Chaperone Machine (Monastery Seeon, Germany). Studies presented under the topic of “extracellular Hsp90 (eHsp90)” at the conference provided direct evidence for eHsp90’s involvement in cancer invasion and skin wound healing. Over the past 15 years, studies have focused on the secretion, action, biological function, therapeutic targeting, preclinical evaluations, and clinical utility of eHsp90 using wound healing, tissue fibrosis, and tumour models both in vitro and in vivo. eHsp90 has emerged as a critical stress-responding molecule targeting each of the pathophysiological conditions. Despite the studies, our current understanding of several fundamental questions remains little beyond speculation. Does eHsp90 indeed originate from purposeful live cell secretion or rather from accidental dead cell leakage? Why did evolution create an intracellular chaperone that also functions as a secreted factor with reported extracellular duties that might be (easily) fulfilled by conventional secreted molecules? Is eHsp90 a safer and more optimal drug target than intracellular Hsp90 chaperone? In this review, we summarize how much we have learned about eHsp90, provide our conceptual views of the findings, and make recommendations on the future studies of eHsp90 for clinical relevance.

Tubular cell-derived exosomal miR-150-5p contributes to renal fibrosis following unilateral ischemia-reperfusion injury by activating fibroblast in vitro and in vivo

Unilateral ischemia reperfusion injury (UIRI) with longer ischemia time is associated with an increased risk of acute renal injury and chronic kidney disease. Exosomes can transport lipid, protein, mRNA, and miRNA to corresponding target cells and mediate intercellular information exchange. In this study, we aimed to investigate whether exosome-derived miRNA mediates epithelial-mesenchymal cell communication relevant to renal fibrosis after UIRI. The secretion of exosomes increased remarkably in the kidney after UIRI and in rat renal tubular epithelium cells (NRK-52E) after hypoxia treatment. The inhibition of exosome secretion by Rab27a knockout or GW4869 treatment ameliorates renal fibrosis following UIRI in vivo. Purified exosomes from NRK-52E cells after hypoxia treatment could activate rat kidney fibroblasts (NRK-49F). The inhibition of exosome secretion in hypoxic NRK-52E cells through Rab27a knockdown or GW4869 treatment abolished NRK-49F cell activation. Interestingly, exosomal miRNA array analysis revealed that miR-150-5p expression was increased after hypoxia compared with the control group. The inhibition of exosomal miR-150-5p abolished the ability of hypoxic NRK-52E cells to promote NRK-49F cell activation in vitro, injections of miR-150-5p enriched exosomes from hypoxic NRK-52E cells aggravated renal fibrosis following UIRI, and renal fibrosis after UIRI was alleviated by miR-150-5p-deficient exosome in vivo. Furthermore, tubular cell-derived exosomal miR-150-5p could negatively regulate the expression of suppressor of cytokine signaling 1 to activate fibroblast. Thus, our results suggest that the blockade of exosomal miR-150-5p mediated tubular epithelial cell-fibroblast communication may provide a novel therapeutic target to prevents UIRI progression to renal fibrosis.

Impact of native and external factors on exosome release: understanding reactive exosome secretion and its biogenesis

Exosomes are minuscule vesicles secreted in the endolytic region of most mammalian cells. The release of exosomes from the cell engenders cell-to-cell signaling between cellular-compartments. The trading of exosomes between tumor and yonder cells plays a hypercritical role in tumor growth and progression. The exosome released from each tumor cell sequestrates a unique biogenetic pathway reflecting its cellular origin depending on the tumor type. However, treatment of tumor cells with certain physiological factors like drugs, chemotherapy, radiation, etc., enhance the release of exosomes and alters its biogenetic pathway compared with untreated tumor cells. In this review, we will discuss how the non-native physiological factors influence the release of exosomes and how these reactive exosomes orchestrate a unique patterning of a cargo sorting mechanism. We will also discuss the role of reactively secreted exosomes in mediating tumor metastasis, angiogenesis, and tumor progression.

Targeting PRAS40: a novel therapeutic strategy for human diseases

Proline-rich Akt substrate of 40 kD (PRAS40) is not only the substrate of protein kinase B (PKB/Akt), but also the binding protein of 14-3-3 protein. PRAS40 is expressed in a variety of tissues in vivo and has multiple phosphorylation sites, which its activity is closely related to phosphorylation. Studies have shown that PRAS40 is involved in regulating cell growth, cell apoptosis, oxidative stress, autophagy and angiogenesis, as well as various of signalling pathways such as mammalian target of mammalian target rapamycin (mTOR), protein kinase B (PKB/Akt), nuclear factor kappa-B(NF-κB), proto-oncogene serine/threonine-protein kinase PIM-1(PIM1) and pyruvate kinase M2 (PKM2). The interactive roles between PRAS40 and these signal proteins were analysed by bioinformatics in this paper. Moreover, it is of great necessity for analyse the important roles of PRAS40 in some human diseases including cardiovascular disease, ischaemia-reperfusion injury, neurodegenerative disease, cancer, diabetes and other metabolic diseases. Finally, the effects of miRNA on the regulation of PRAS40 function and the occurrence and development of PRAS40-related diseases are also discussed. Overall, PRAS40 is expected to be a drug target and provide a new treatment strategy for human diseases.

Emerging role of tumor microenvironment derived exosomes in therapeutic resistance and metastasis through epithelial-to-mesenchymal transition

The tumor microenvironment (TME) constitutes multiple cell types including cancerous and non-cancerous cells. The intercellular communication between these cells through TME derived exosomes may either enhance or suppress the tumorigenic processes. The tumor-derived exosomes could convert an anti-tumor environment into a pro-tumor environment by inducing the differentiation of stromal cells into tumor-associated cells. The exosomes from tumor-associated stromal cells reciprocally trigger epithelial-to-mesenchymal transition (EMT) in tumor cells, which impose therapeutic resistance and metastasis. It is well known that these exosomes contain the signals of EMT, but how these signals execute chemoresistance and metastasis in tumors remains elusive. Understanding the significance and molecular signatures of exosomes transmitting EMT signals would aid in developing appropriate methods of inhibiting them. In this review, we focus on molecular signatures of exosomes that shuttle between cancer cells and their stromal populations in TME to explicate their impact on therapeutic resistance and metastasis through EMT. Especially Wnt signaling is found to be involved in multiple ways of exosomal transport and hence we decipher the biomolecules of Wnt signaling trafficked through exosomes and their potential in serving as therapeutic targets.

The roles of tumor-derived exosomes in altered differentiation, maturation and function of dendritic cells

Tumor-derived exosomes (TDEs) have been shown to impede anti-tumor immune responses via their immunosuppressive cargo. Since dendritic cells (DCs) are the key mediators of priming and maintenance of T cell-mediated responses; thus it is logical that the exosomes released by tumor cells can exert a dominant influence on DCs biology. This paper intends to provide a mechanistic insight into the TDEs-mediated DCs abnormalities in the tumor context. More importantly, we discuss extensively how tumor exosomes induce subversion of DCs differentiation, maturation and function in separate sections. We also briefly describe the importance of TDEs at therapeutic level to help guide future treatment options, in particular DC-based vaccination strategy, and review advances in the design and discovery of exosome inhibitors. Understanding the exosomal content and the pathways by which TDEs are responsible for immune evasion may help to revise treatment rationales and devise novel therapeutic approaches to overcome the hurdles in cancer treatment.

Mutant p53 Drives Cancer Metastasis via RCP-Mediated Hsp90α Secretion

Mutant p53 (mutp53) loses its tumor suppressor properties but gains oncogenic functions of driving malignancy. However, it remains largely unknown how mutp53 drives cancer metastasis. Here, we show that wild-type p53 (WTp53) suppresses the secretion of heat shock protein 90-alpha (Hsp90α), whereas mutp53 enhances Hsp90α vesicular trafficking and exosome-mediated secretion. Long-term delivery of an antibody that blocks extracellular Hsp90α (eHsp90α) function extends the survival of p53^-/- mice and attenuates the invasiveness of p53 mutant tumors. Furthermore, mass spectrometry and functional analysis identified a critical role for Rab coupling protein (RCP) in mutp53-induced Hsp90α secretion. RCP knockdown decreases eHsp90α levels and inhibits malignant progression. Notably, recombinant Hsp90α re-introduction markedly rescues the impaired migration and invasion abilities caused by RCP depletion. Taken together, these findings elucidate the molecular mechanisms by which mutp53 executes oncogenic activities via its downstream RCP-mediated Hsp90α secretion and a strategy to treat human cancers expressing mutp53 proteins.

Trends in Research on Exosomes in Cancer Progression and Anticancer Therapy

Simple Summary

Intensive research in the field of cancer biology has discovered a unique mode of interplay between cells via extracellular bioactive vesicles called exosomes. Exosomes serve as intermediators among cells via their cargoes that, in turn, contribute in the progression of cancer. They are ubiquitously present in all body fluids as they are secreted from both normal and tumor cells. These minuscules exhibit multiple unique properties that facilitate their migration to distant locations and modulate the microenvironment for progression of cancer. This review summarizes the multifarious role of exosomes in various aspects of cancer research with its pros and cons. It discusses biogenesis of exosomes, their functional role in cancer metastasis, both protumorigenic and antitumorigenic, and also their applications in anticancer therapy.

Abstract

Exosomes, the endosome-derived bilayered extracellular nanovesicles with their contribution in many aspects of cancer biology, have become one of the prime foci of research. Exosomes derived from various cells carry cargoes similar to their originator cells and their mode of generation is different compared to other extracellular vesicles. This review has tried to cover all aspects of exosome biogenesis, including cargo, Rab-dependent and Rab-independent secretion of endosomes and exosomal internalization. The bioactive molecules of the tumor-derived exosomes, by virtue of their ubiquitous presence and small size, can migrate to distal parts and propagate oncogenic signaling and epigenetic regulation, modulate tumor microenvironment and facilitate immune escape, tumor progression and drug resistance responsible for cancer progression. Strategies improvised against tumor-derived exosomes include suppression of exosome uptake, modulation of exosomal cargo and removal of exosomes. Apart from the protumorigenic role, exosomal cargoes have been selectively manipulated for diagnosis, immune therapy, vaccine development, RNA therapy, stem cell therapy, drug delivery and reversal of chemoresistance against cancer. However, several challenges, including in-depth knowledge of exosome biogenesis and protein sorting, perfect and pure isolation of exosomes, large-scale production, better loading efficiency, and targeted delivery of exosomes, have to be confronted before the successful implementation of exosomes becomes possible for the diagnosis and therapy of cancer.

The forces driving cancer extracellular vesicle secretion

The discovery that cancer cells discharge vast quantities of extracellular vesicles (EVs), underscored the explosion of the EV field. A large body of evidence now supports their onco-functionality in an array of contexts; stromal crosstalk, immune evasion, metastatic site priming, and drug resistance - justifying therapeutic intervention. The current bottleneck is a lack of clear understanding of why and how EV biogenesis ramps up in cancer cells, and hence where exactly avenues for intervention may reside. We know that EVs also play an array of physiological roles, therefore effective anticancer inhibition requires a target distinct enough from physiology to achieve efficacy. Taking the perspective that EV upregulation may be a consequence of the tumor landscape, we examine classic mutational events and tumor characteristics for EV regulators. All the while, aiming to illuminate topics worth further research in therapeutic development.

Cooperation and Interplay between EGFR Signalling and Extracellular Vesicle Biogenesis in Cancer

Epidermal growth factor receptor (EGFR) takes centre stage in carcinogenesis throughout its entire cellular trafficking odyssey. When loaded in extracellular vesicles (EVs), EGFR is one of the key proteins involved in the transfer of information between parental cancer and bystander cells in the tumour microenvironment. To hijack EVs, EGFR needs to play multiple signalling roles in the life cycle of EVs. The receptor is involved in the biogenesis of specific EV subpopulations, it signals as an active cargo, and it can influence the uptake of EVs by recipient cells. EGFR regulates its own inclusion in EVs through feedback loops during disease progression and in response to challenges such as hypoxia, epithelial-to-mesenchymal transition and drugs. Here, we highlight how the spatiotemporal rules that regulate EGFR intracellular function intersect with and influence different EV biogenesis pathways and discuss key regulatory features and interactions of this interplay. We also elaborate on outstanding questions relating to EGFR-driven EV biogenesis and available methods to explore them. This mechanistic understanding will be key to unravelling the functional consequences of direct anti-EGFR targeted and indirect EGFR-impacting cancer therapies on the secretion of pro-tumoural EVs and on their effects on drug resistance and microenvironment subversion.

Duchenne muscular dystrophy (DMD) cardiomyocyte-secreted exosomes promote the pathogenesis of DMD-associated cardiomyopathy

Cardiomyopathy is a leading cause of early mortality in Duchenne muscular dystrophy (DMD). There is a need to gain a better understanding of the molecular pathogenesis for the development effective therapies. Exosomes (exo) are secreted vesicles and exert effects via their RNA, lipid and protein cargo. The role of exosomes in disease pathology is unknown. Exosomes derived from stem cells have demonstrated cardioprotection in the murine DMD heart. However, it is unknown how the disease status of the donor cell type influences exosome function. Here, we sought to determine the phenotypic responses of DMD cardiomyocytes (DMD-iCMs) after long-term exposure to DMD cardiac exosomes (DMD-exo). DMD-iCMs were vulnerable to stress, evidenced by production of reactive oxygen species, the mitochondrial membrane potential and cell death levels. Long-term exposure to non-affected exosomes (N-exo) was protective. By contrast, long-term exposure to DMD-exo was not protective, and the response to stress improved with inhibition of DMD-exo secretion in vitro and in vivo The microRNA (miR) cargo, but not exosome surface peptides, was implicated in the pathological effects of DMD-exo. Exosomal surface profiling revealed N-exo peptides associated with PI3K-Akt signaling. Transcriptomic profiling identified unique changes with exposure to either N- or DMD-exo. Furthermore, DMD-exo miR cargo regulated injurious pathways, including p53 and TGF-beta. The findings reveal changes in exosomal cargo between healthy and diseased states, resulting in adverse outcomes. Here, DMD-exo contained miR changes, which promoted the vulnerability of DMD-iCMs to stress. Identification of these molecular changes in exosome cargo and effectual phenotypes might shed new light on processes underlying DMD cardiomyopathy.This article has an associated First Person interview with the first author of the paper.

Targeting IL-3Rα on tumor-derived endothelial cells blunts metastatic spread of triple-negative breast cancer via extracellular vesicle reprogramming

The lack of approved targeted therapies highlights the need for new treatments for triple-negative breast cancer (TNBC) patients. Interleukin-3 (IL-3) acts as an autocrine factor for tumor-endothelial cells (TEC), and exerts pro-angiogenic paracrine action via extracellular vesicles (EVs). IL-3Rα blockade on TEC changes TEC-EV (anti-IL-3R-EV) microRNA (miR) content and promotes the regression of established vessels. As TEC is the doorway for "drug" entry into tumors, we aimed to assess whether IL-3R blockade on TEC impacts tumor progression via its unique EV cargo. First, the expression of IL-3Rα was evaluated in 27 human TNBC samples. It was noticed that, besides TEC and inflammatory cells, tumor cells from 55.5% of the human TNBC samples expressed IL-3Rα. Using human TNBC cell lines for in vitro studies, we found that, unlike native TEC-EVs (nEVs), anti-IL-3R-EVs increase apoptosis and reduced cell viability and migration. In vivo, anti-IL-3R-EV treatment induced vessel regression in established tumors formed of MDA-MB-231 cells, decreased Vimentin, β-catenin, and TWIST1 expression, almost abolished liver and lung metastases from primary tumors, and reduced lung metastasis generated via the intravenous injection of MDA-MB-231 cells. nEVs depleted of miR-24-3p (antago-miR-24-3p-EVs) were effective as anti-IL-3R-EVs in downregulating TWIST1 and reducing metastatic lesions in vivo. Consistent with network analyses of miR-24-3p gene targeting, anti-IL-3R-EVs and antago-miR-24-3p-EVs upregulate SPRY2 in MDA-MB-231 cells. Finally, SPRY2 silencing prevented anti-IL-3R-EV and antago-miR-24-3p-EV-mediated apoptotic cues.Overall, these data provide the first evidence that IL-3Rα is highly expressed in TNBC cells, TEC, and inflammatory cells, and that IL-3Rα blockade on TEC impacts tumor progression.

Extracellular Vesicles in Renal Cell Carcinoma: Multifaceted Roles and Potential Applications Identified by Experimental and Computational Methods

Renal cell carcinoma (RCC) is the most common type of kidney cancer. Increasingly evidences indicate that extracellular vesicles (EVs) orchestrate multiple processes in tumorigenesis, metastasis, immune evasion, and drug response of RCC. EVs are lipid membrane-bound vesicles in nanometer size and secreted by almost all cell types into the extracellular milieu. A myriad of bioactive molecules such as RNA, DNA, protein, and lipid are able to be delivered via EVs for the intercellular communication. Hence, the abundant content of EVs is appealing reservoir for biomarker identification through computational analysis and experimental validation. EVs with excellent biocompatibility and biodistribution are natural platforms that can be engineered to offer achievable drug delivery strategies for RCC therapies. Moreover, the multifaceted roles of EVs in RCC progression also provide substantial targets and facilitate EVs-based drug discovery, which will be accelerated by using artificial intelligence approaches. In this review, we summarized the vital roles of EVs in occurrence, metastasis, immune evasion, and drug resistance of RCC. Furthermore, we also recapitulated and prospected the EVs-based potential applications in RCC, including biomarker identification, drug vehicle development as well as drug target discovery.

Changes in mediators of pro-cell growth, senescence, and inflammation during murine gestation

PROBLEM

Senescence of the fetal membranes and senescence-associated inflammation have been associated with parturition at term and pre-term in both mice and humans. Using a pregnant mouse model, we determined changes in multiple molecular signalers contributing to senescence and inflammation associated with parturition.

METHOD OF STUDY

Fetal membranes were collected from timed-pregnant CD-1 mice on gestation days (E) 13, 15, 17, 18, and 19. Immunohistochemistry (IHC) localized pro-cell growth factors glycogen synthase kinase 3β (GSK3β) and β-catenin. Gestational age-associated changes in pro-cell growth vs senescence mediators (p38 mitogen-activated protein kinase [p38MAPK]), prooxidants (heme oxygenase-1 [HO-1], peroxisome proliferator-activated receptor γ [PPARγ]), and pro- and anti-inflammatory cytokines (IL-6, IL-8, IL-10, and IL-1β) were determined by Western blots and Luminex assays.

RESULTS

Fetal membrane expressions of phosphorylated forms of GSK3β (inactivation) and p38MAPK (activation) increased, while β-catenin expression decreased, as gestation progressed. Antioxidant HO-1 expression decreased while PPARγ increased toward term gestation. IL-6 and IL-8 concentrations were highest on E19 (day of delivery), while IL-10 and IL-1β concentrations were highest on E15.

CONCLUSION

Mouse fetal membranes showed a progressive senescence marker increase coincided with downregulation of cell growth factors. Development of senescence is associated with inflammation. Senescence-associated changes are natural and physiologic and indicative of fetal membranes' readiness for parturition.

Tumour-Secreted Hsp90α on External Surface of Exosomes Mediates Tumour - Stromal Cell Communication via Autocrine and Paracrine Mechanisms

Extracellular heat shock protein-90alpha (eHsp90α) plays an essential role in tumour invasion and metastasis. The plasma eHsp90α levels in patients with various cancers correlate with the stages of the diseases. Nonetheless, the mechanism of action by tumour-secreted eHsp90α remained unclear. Here we show that eHsp90α accounts for approximately 1% of the total cellular Hsp90α and is associated with tumour-secreted exosomes. CRISPR-cas9 knockout of Hsp90α did not affect the overall distribution and quantity of secreted exosomes, but it caused increased exosome-associated CD9 and decreased exosome-associated TSG101, Alix, and CD63. However, Hsp90α-knockout tumour cells have not only lost their own constitutive motility, but also the ability to recruit stromal cells via secreted exosomes. These defects are specifically due to the lack of eHsp90α on tumour cell-secreted exosomes. Anti-Hsp90α antibody nullified the pro-motility activity of tumour-secreted exosomes and human recombinant Hsp90α protein fully rescued the functional defects of eHsp90α-free exosomes. Finally, while current exosome biogenesis models exclusively implicate the luminal location of host cytosolic proteins inside secreted exosomes, we provide evidence for eHsp90α location on the external surface of tumour-secreted exosomes. Taken together, this study elucidates a new mechanism of action by exosome-associated eHsp90α.

A review on protein markers of exosome from different bio-resources and the antibodies used for characterization

Exosomes are small membrane vesicles (ranging from 30 nm to 150 nm), secreted by different cell types upon fusion of multivesicular bodies (MVB) to the cell plasma membrane under a variety of normal and pathological conditions. Through transferring their cargos such as proteins, lipids and nucleic acids from donor cells to recipient cells, exosomes play a crucial role in cell-to-cell communication. Due to their presence in most body fluids (such as blood, breast milk, saliva, urine, bile, pancreatic juice, cerebrospinal and peritoneal fluids), and their role in carrying bioactive molecules from the cells of origin, exosomes have attracted great interest in their diagnostic and prognostic value for various diseases and therapeutic approaches. Although a large body of literature has documented the importance of exosomes over the past decade, there is no article systematically summarizing protein markers of exosome from different resources and the antibodies that are suited to characterize exosomes. In this review, we briefly summarize the exosome marker proteins, exosomal biomarkers for different diseases, and the antibodies suitable for different bio-resources exosomes characterization.

After Conventional Wisdom Has Failed, What Drives Wound Healing?

Between 2006 and 2015, the U.S. Food and Drug Administration’s (FDA) overall likelihood of approval (LOA) from Phase I clinical trials for all therapeutic candidates was 9.6%, with the highest LOA in haematology (26.1%) and the lowest in oncology (5.1%). Two critical features attributed to the success of advancing trials were i) targeting driver genes responsible for disease, and ii) use of human disease-relevant animal models during preclinical studies. For decades, conventional wisdom has been that growth factors are the drivers of wound healing, but few have either advanced to clinical applications or proven effective. The purpose of this paper is to explore heat shock protein 90-alpha (Hsp90α)’s role as a potential driver of wound healing and as a possible future therapeutic entity through a review of recent literature, including studies with human disease-relevant animal models. Of the approximately 7,000 gene products generated by a given mammalian cell type, the Hsp90 family of proteins (Hsp90α and Hsp90β) accounts for 2–3% of them. Hsp90β fulfils the role of an intracellular chaperone, but Hsp90α’s intracellular function is surprisingly dispensable. Instead, the abundancy of Hsp90α appears to have been prepared for extracellular purposes. When secreted via exosomes by cells under environmental stress, such as injury, Hsp90α protects cells from hypoxia-induced cell death, reduces local inflammation, and subsequently promotes cell migration to repair the injured tissue. Unlike conventional growth factors, secreted Hsp90α stimulates all major cell types involved in wound healing equally, resists microenvironmental inhibitors like TGFβ and hyperglycaemia, and is highly stable. Inhibition of exosome-mediated Hsp90α secretion, neutralisation of Hsp90α’s ATPase-independent extracellular functions, or interruption of Hsp90α-LRP-1 signalling blocks wound closure in vivo. Topical application of Hsp90α’s therapeutic entity, F-5 (a 115-amino acid peptide), has shown great promise for healing acute burn and diabetic wounds in mice and pigs.

LncRNA HOTAIR in Tumor Microenvironment: What Role?

lncRNAs participate in many cellular processes, including regulation of gene expression at the transcriptional and post-transcriptional levels. In addition, many lncRNAs can contribute to the development of different human diseases including cancer. The tumor microenvironment (TME) plays an important role during tumor growth and metastatic progression, and most of these lncRNAs have a key function in TME intracellular signaling. Among the numerous identified lncRNAs, several experimental evidences have shown the fundamental role of the lncRNA HOTAIR in carcinogenesis, also highlighting its use as a circulating biomarker. In this review we described the contribution of HOTAIR in the TME modulation, highlighting its relation with cellular and non-cellular components during tumor evolution and progression.

Exosome-orchestrated hypoxic tumor microenvironment

Hypoxic tumor microenvironment is a common feature of solid tumors and is associated with aggressiveness and poor patient outcomes. A continuous interference between cancer cells and stromal cells within the hypoxic microenvironment has been uncovered for its importance in cancer development and treatment responsiveness. Exosomes, initially considered as “garbage bins” for unwanted material from cells, are now elucidated to perform a variety of functions that involve interactions within the cellular microenvironment due to their ability to carry numerous cargoes, including lipids, proteins, nucleic acids, and metabolites. Exosome-mediated continuous interference between cancer cells and stroma are believed to regulate hypoxia-adaptation and to rebuild the microenvironment in return. In this review, we will discuss the knowledge in literature with respect to the exosome-mediated multi-directional and mutual signal transmission among the variety of cell types within hypoxic cancer microenvironment.

Modifying exosome release in cancer therapy: How can it help?

The reciprocal interactions of cancer cells with their microenvironment constitute an inevitable aspect of tumor development, progression and response to treatment in all cancers. Such bilateral transactions also serve as the key scenario underlying the development of drug resistance in many cases finally determining the fate of the disease and survival. In this view, a class of extracellular vesicles (EV) known as exosomes (EX) have been shown in the past few years to be important mediators of local and remote cell-to-cell contact changing the activity of their target cells by introducing their content of proteins, non-coding RNAs, and membrane-associated small molecules. In addition to the direct targeting of cancer cells, which has been routinely undertaken by different means to date, parallel attempts to change the signaling network governed by tumor-derived exosomes (TDE) may offer a promising potential to be utilized in cancer therapy. TDE drive diverse functions in the body, most of which have been shown to act to the advantage of tumor progression; however, there are also several studies that report the good aspects of TDE the interruption of which may result in undesirable outcomes. In the present paper, we made an effort to address this important issue by reviewing the very recent literature on different aspects of EX biogenesis and regulation and the various bodily effects of TDE which have been uncovered to date. Moreover, we have reviewed the possible interventions that can be made in TDE release as an important stage of EX biogenesis. Finally, keeping a criticizing view, the advantages and disadvantages of such interventions have been discussed and the future prospect in the field has been outlined.

Extracellular Vesicles: A New Perspective in Tumor Therapy

In recent years, the study of extracellular vesicles has been booming across various industries. Extracellular vesicles are considered one of the most important physiological endogenous carriers for the specific delivery of molecular information (nucleonic acid, cytokines, enzymes, etc.) between cells. It has been discovered that they perform a critical role in promoting tumor cell growth, proliferation, tumor cell invasion, and metastatic ability and regulating the tumor microenvironment to promote tumor cell communication and metastasis. In this review, we will discuss (1) the mechanism of extracellular vesicles generation, (2) their role in tumorigenesis and cancer progression (cell growth and proliferation, tumor microenvironment, epithelial-mesenchymal transition (EMT), invasion, and metastasis), (3) the role of extracellular vesicles in immune therapy, (4) extracellular vesicles targeting in tumor therapy, and (5) the role of extracellular vesicles as biomarkers. It is our hope that better knowledge and understanding of the extracellular vesicles will offer a wider range of effective therapeutic targets for experimental tumor research.

Biogenesis and function of extracellular vesicles in cancer

Extracellular vesicles (EVs) are heterogeneous multi-signal messengers that support cancer growth and dissemination by mediating the tumor-stroma crosstalk. Exosomes are a subtype of EVs that originate from the limiting membrane of late endosomes, and as such contain information linked to both the intrinsic cell "state" and the extracellular signals cells received from their environment. Resolving the signals affecting exosome biogenesis, cargo sorting and release will increase our understanding of tumorigenesis. In this review we highlight key cell biological processes that couple exosome biogenesis to cargo sorting in cancer cells. Moreover, we discuss how the bidirectional communication between tumor and non-malignant cells affect cancer growth and metastatic behavior.

The role of secreted heat shock protein-90 (Hsp90) in wound healing - how could it shape future therapeutics?

INTRODUCTION

Defects in tissue repair or wound healing pose a clinical, economic and social problem worldwide. Despite decades of studies, there have been few effective therapeutic treatments. Areas covered: We discuss the possible reasons for why growth factor therapy did not succeed. We point out the lack of human disorder-relevant animal models as another blockade for therapeutic development. We summarize the recent discovery of secreted heat shock protein-90 (Hsp90) as a novel wound healing agent. Expert commentary: Wound healing is a highly complex and multistep process that requires participations of many cell types, extracellular matrices and soluble molecules to work together in a spatial and temporal fashion within the wound microenvironment. The time that wounds remain open directly correlates with the clinical mortality associated with wounds. This time urgency makes the healing process impossible to regenerate back to the unwounded stage, rather forces it to take many shortcuts in order to protect life. Therefore, for therapeutic purpose, it is crucial to identify so-called 'driver genes' for the life-saving phase of wound closure. Keratinocyte-secreted Hsp90α was discovered in 2007 and has shown the promise by overcoming several key hurdles that have blocked the effectiveness of growth factors during wound healing.